THE KARSTIC MASSIFS OF WESTERN ALPS: structural and bioclimatic framework - The structural conditions determine several types of karst units: the northern Prealps (thrusts), the southern Jura (folded or tabular), the southern Prealps (faulted and folded plateaus), the complex land of Low Provence, and the high karsts of Inner Alps. The bioclimatic framework explains the altitudinal sequence of current processes. The value of the runoff, the part of the snow, and the biochemical parameters (vegetation, CO2), have particularly holded the attention. The specific dissolution reaches its maximum in the wooded mountain karsts. Heritages also determine the landforms (glacial, periglacial, terra-rossa).